The British go to the polls May 6 after one of their trademark brisk election campaigns. But as Americanisms creep into their politics, British voters are girding for a completely American experience — the first prime ministerial debates in history, beginning Thursday.

These debates will come at a poignant time in American history, the 50th anniversary of the first debates in the United States. Though political debates now have become a permanent feature of our elections, they were a brave innovation when Vice President Richard M. Nixon and Sen. John F. Kennedy inaugurated a new era in American history with four debates in September and October 1960.

Those debates would be unrecognizable to Americans today, who live in a faster culture and have shorter attention spans. Nixon and Kennedy opened the first session with eight-minute statements and were given two and a half minutes to respond to questions from panelists led by Howard K. Smith of CBS News. The British debaters will be given only one minute to answer each question.

No longer real debates

“I’ve got doubts about the debates, because they are not debates anymore,” said Sander Vanocur, 82, the former NBC newsman and the only participant in the 1960 debates still alive. “They were real debates when we started out. But they have gone downhill, or at least in a different direction. They have become shows, performances. These things are no longer designed to bring out differences and answers, but just to score points.”

The 1960 debates were thrown together with relative informality and ease; this was, after all, before anyone knew of the politically transformative effect of a line of perspiration on a vice president’s forehead, the political disadvantage inherent in a 5 o’clock shadow or the influence of pancake makeup on history.

Indeed, it is ironic to remember that Nixon entered the debate as by far the greatest beneficiary of television politics until that time, having salvaged his career and his vice presidential nomination eight years earlier with his Checkers speech.

The British debates will last 90 minutes and the composition of the audience has been meticulously negotiated: 29.5 percent Labor voters, 29.5 percent Conservative voters, 21 percent Liberal Democrats and 20 percent undecided. The audience can applaud only as the debate begins and ends, and a panel of experts will review the questions for fairness. Good luck with that.

Powerful influence

It is impossible to overestimate how profoundly the 1960 debates changed American politics, underlining the importance of personal appeal, charm and charisma, rewarding the sharp remark or riposte, adding a cosmetic and confectionery tone to politics.

But the debates were considered so powerful and so unpredictable a force that President Lyndon B. Johnson refused to risk one against Sen. Barry Goldwater in 1964, and Nixon — by now justifiably skittish of televised debates — refused to engage Vice President Hubert H. Humphrey and Gov. George C. Wallace in debates in 1968 and Sen. George S. McGovern in 1972. Since then, however, there have been debates in every presidential election and vice presidential debates in most.

“It’s impossible for a candidate today not to participate,” Newton N. Minow, who pushed Congress to change the equal-time law to permit the 1960 debates and later became chairman of the Federal Communications Commission, said in an interview. “It is an established, permanent part of the American election system.”

Most analysts agree that Nixon was slightly better prepared than Kennedy in 1960 but far less appealing. Those who listened to the first debate generally considered Nixon the winner. Those who watched it on television considered Kennedy the winner. Russell Baker, The New York Times reporter who covered the debates, recalled in his memoir that he kept his head down during the event, listening, taking notes and typing. “I thought Nixon had a slight edge in what little argument there had been,” he wrote.

By mid-October 1960, the candidates were arguing over Quemoy and Matsu, two islands off the coast of China that dominated the third debate and have since become the answer to a beloved Cold War-era trivia question. The moderators and questioners at these sessions were all men. Four of the news outlets they represented have been out of business for decades. Some of the participants are regarded as giants in American journalism, including Walter Cronkite, John Chancellor, Frank McGee and Roscoe Drummond.

British rules

The British parties agreed to their debates after sealing a 76-clause deal to govern the conduct of the sessions. With that many rules, the greatest threat may be that the debates will bore viewers to death.

Even so, the participants are unsettled by this innovation. “You bet I’m nervous about it; you’d have to be inhuman not to be nervous about an occasion like this,” Conservative leader David Cameron told Sky News last week, “but the opportunity to say what you think and to tell people why you want to be prime minister, why you think you’ve got the right values, you’ve got the right team, the right policies, it’s a great opportunity.”

Yes, but former Democratic Sen. Paul G. Kirk Jr. of Massachusetts, who for 22 years was co-chairman of the nonpartisan Commission on Presidential Debates, questions the extent to which candidates can tailor debates to their own purposes.

“The opening and closing statements are their best bet,” he said, “but on the give-and-take and the question-and-answers it’s a lot more difficult than it looks to articulate your core message. It’s the highest pressure situation with the highest stakes you can have in politics. This is as close to an unvarnished, extemporaneous exchange as there is.”

That, of course, is the great trap of political debates — the participants always think they can control the uncontrollables.